A conventional axial flow gas turbine engine comprises, in axial flow series, a compressor section, a combustor in which compressed air from the high pressure compressor is mixed with fuel and burnt and a turbine section driven by the products of combustion.
The products of combustion pass from the combustor to the first stage of the turbine through an array of nozzle guide vanes. Aerodynamic losses are experienced as the products of combustion pass from the combustor to the nozzle guide vanes. The aerodynamic losses produce a circumferential pressure gradient close to the leading edge of the nozzle guide vane. This pressure gradient prevents cooling air from flowing uniformly over the platform of the nozzle guide vane. As the cooling air does not flow uniformly over the platform hot combustion gases can impinge on the platform surface and cause hot streaks on the platform of the nozzle guide vane. This is detrimental to component performance and life.